Diverse match plate molding machines are conventionally used for producing sand molds. One typical example of the match plate molding machine of the type in which the direction of incoming of sand into a molding cavity of a molding flask is at substantially right angles to the direction of squeezing the sand within the molding cavity is disclosed in Japanese Laid-Open patent application No. 54(1979)-110126. A description of the conventional match plate molding machine of the type disclosed in the above-mentioned Japanese patent application No. 54(1979)-110126, will be set forth hereinbelow with reference to FIG. 1.
In the conventional match plate molding machine illustrated in FIG. 1, a match plate 2 provided with a pattern 1 is brought into a molding position where the match plate 2 is tightly held between or sandwiched by a molding flask 3 for an upper mold and a molding flask 4 for a lower mold. The pair of molding flasks 3 and 4 are arranged in a working area established by a rigid machine framework having vertical columns 13 so that the molding flasks 3 and 4 are laterally movable toward and away from one another by the actuation of fluid cylinder devices along a horizontal guide 14. After completion of positioning of the match plate 2 and the molding flasks 3 and 4 into the molding position, a squeeze plate 5 for an upper mold and a squeeze plate 6 for a lower mold are laterally moved by the actuation of fluid cylinders 16 and 17 until the squeeze plates 5 and 6 come into respective predetermined positions inside the molding flasks 3 and 4. Thus, within both molding flasks 3 and 4, a molding cavity 7 for an upper mold and a molding cavity 8 for a lower mold are defined. At this stage, a telescopic sprue-forming rod 9 attached to the squeeze plate 5 is abutted against the match plate 2. Subsequently, sand is supplied from a sand blower 10 into the molding cavities 7 and 8 through a sand inlet port 11 formed in a part of a side wall of the molding flask 3 and a sand inlet port 12 formed in a part of a side wall of the molding flask 4. Upon completion of filling the molding cavities 7 and 8 with the sand, respective squeeze plates 5 and 6 are advanced by the actuation of respective fluid cylinders 16 and 17 toward the match plate 2 so that the filled sand within the molding cavities 7 and 8 is compacted or squeezed by the squeeze plates 5 and 6. It sould here be noted that the direction of incoming of sand from the sand blower 10 into respective molding cavities 7 and 8 is vertical, while the direction of squeezing the sand within the molding cavities 7 and 8 is horizontal. Therefore, as illustrated in FIG. 1, a horizontal and deep pocketed cavity A formed in the pattern 1 and corners B and C adjacent to the pattern 1 are not filled with a sufficient amount of the sand during the supply of the sand from the sand blower 10. As a result, even after completion of squeezing of the sand by the squeeze plates 5 and 6, frequently either a sand mold having a desired shape accurately complementary to the shape of the pattern 1 cannot be produced or collapsing of a sand mold occurs due to lack of physical strength of the mold during the parting process of the sand mold. Further cracks or breakage of a sand mold frequently occur during the pouring process, thus causing a defect or defects in a molded product. Therefore, in order to obviate the defects encountered with the conventional match plate molding machine of the type illustrated in FIG. 1, it is strongly desired to provide an appropriate method for enabling a sufficient filling of sand into the entire molding cavity of a molding flask, including a deep pocketed cavity or cavities of a pattern, as well as every corner of the pattern, for the purpose of eventually producing a sand mold having a high physical strength. It is further desired to devise an appropriate means for carrying out the above-mentioned method.